Procaine salts of biosynthetic penicillins



l atented Oct. 31, 1950 PRooAI s same or BIOSYNTHETIC PENICILLINS.

Harley W. Rhodchamel, Jr., Indianapolis, Ind., assignor to Eli Lilly and Company, Indianapolis, Ind., a corporation of Indiana No Drawing. Application July 1, 1948, Serial No. 36,456

4 Claims. (Cl. 260302) My invention relates to salts of biosynthetic penicillins :and more particularly to insoluble salts of aliphatic and carbocyclic mercaptomethyl penicillins.

An object of my invention is to prepare insoluble salts of aliphatic and carbocyclic mercaptomethyl penicillins. Another object is to provide insoluble salts useful in the isolation and purification of biosynthetic penicillins. Another object is to provide insoluble salts of biosynthetic mercaptomethyl penicillins which have a prolonged therapeutic efiect. Other objects will be apparent from the following disclosure of my invention.

I have discovered that aliphatic and carbocyclic mercaptomethyl penicillins form crystalline salts with procaine and that such salts possess properties whereby the above and other objects are accomplished.

The novel salts of my invention may be represented by the following formula wherein R represents a member of the group consisting of aliphatic hydrocarbon radicals having from 2 to 6 carbon atoms, saturated carbocyclic hydrocarbon radicals having from 5 to 6 carbon atoms in the ring and a total of from 5 to 7 carbon atoms, and the monohalogen substitution products of said radicals.

Illustrative examples of compounds within the scope of my invention are the procaine salts of allylmercaptomethyl penicillin, nbutylmercaptomethyl penicillin, cyclopentylmercaptomethyl penicillin, 2-ethylbutylmercaptomethyl penicillin and 2-methylcyclohexylmercaptomethyl penicillin.

The biosynthetic mercaptomethyl penicillins used in producing the salts of my invention may be obtained by growing a penicillin-producing mold in a culture medium containing a suitable precursor compound which the mold may metabolize and incorporate in the biosynthetic penicillin. Proceduresfor the preparation of the biopenicillin may be reacted with procaine base, or a soluble metallic or metalline (e. g. ammonium) salt of the biosynthetic penicillin may be reacted with a soluble acid addition salt of procaine. Thus, for example, the acidic form of the biosynthetic penicillin and procaine base are mixed together in amyl acetate to yield as a precipitate, the desired procaine salt of the biosynthetic penicillin. Alternatively the sodium salt of the biosynthetic penicillin and procaine hydrochloride are reacted in aqueous solution to yield the insoluble procaine salt. The insoluble salt which precipitates is isolated, as by filtration, and freed from traces of solvent in any suitable manner, such as subjecting the salt to a vacuum.

I It is desirable to employ an amount of procaine salt or procaine base in slight stoichiometric excess to assure the complete reaction of all of the biosynthetic penicillin present. The procaine salts of this invention being substantially insoluble in water and the common organic solvents, precipitate when prepared in one of these solvents, leaving the excess procaine or soluble salt thereof in solution. It is believed that the procaine salt of the biosynthetic penicillin comprises the combination of the acidic carboxyl group of the penicillin with the basic nitrogen of the diethylaminoethyl group in the procaine molecule.

The biosynthetic penicillin may be recovered from its combination with procaine by dissolving or suspending the procaine salt in aqueous solution, acidifying the solution to about pH 2, and extracting the biosynthetic penicillin with a penicillin solvent such as amyl acetate, chloroform and the like. From the solution thus obtained the biosynthetic enicillin may be recovered by anyof the several suitable known processes. 7

The following examples describe specific preparations of several salts of my invention.

Example 1 The procaine salt of allylmercaptomethyl penisynthetic penicillins are described in detail in cillin represented by the formula the publication by Behrens et al., J. Biol. Chem, 175,793 (1948).

The above-mentioned procaine salts of biosynthetic mercaptomethyl penicillins may be prepared by chemical reactions of addition or metathesis. The acidic form of the ,biosynthetic o- '-CH.H2N g OOH is obtained as follows:

The allylmercaptomethyl penicillin used in preparing the above salt can be produced by growing a penicillin-producing mold in a culture medium containing about 0.02 percent of N-(2- hydroxyethyl) allylmercaptoacetamide, The

allylmercaptoniethyl penicillin produced in the broth is isolated as the sodium salt.

To about 5.2 parts of the sodium salt of the allylmercaptomethyl penicillin dissolved in about 30 parts of water is added a solution of about 5 parts (20 percent excess) of procaine hydrochloride in 15 parts of water. An immediate crystalline precipitate of the procaine salt of allylmercaptomethyl penicillin separates. The mixture is cooled to about 0 C. for about 2 hours and is then filtered to separate the insoluble procaine salt of allylmercaptomethyl penicillin. The separated salt is washed with a small amount of cold water and is then dried in vacuo. About 6.5 parts of the procaine salt of allylmercaptomethyl penicillin are obtained.

ExampleZ The procaine salt of fl-bromoallylmeroaptoslowly and with stirring 100 cc. of amyl acetate containing about 2.5 g. of procaine base. The procaine salt of n-butylmercaptomethyl penicillin precipitates in crystalline form. The solution is cooled to about 0 C. for about 2 hours and is then filtered to isolate the precipitated procaine salt of n-butylmercaptomethyl penicillin. The isolated crystalline salt is washed with a small amount of cold amyl acetate and dried 10 in vacuo to remove traces of moisture and residual amyl acetate.

The n-butylmercaptomethyl penicillin is recovered from its insoluble procaine salt as follows: 2 g. of the procaine salt are suspended in is about 50 ml. of cold water and suificient dilute sulfuric acid is added slowly to acidify the solution to about pH 2. The acidified mixture is extracted with about 50 ml. of amyl acetate whereupon the n-butylmercaptomethyl penicillin methyl penicillin represented by the following 3*. dissolves in the amyl acetate, and the procaine formula COOH Example 3 Instead of using a soluble salt of the penicillin and a procaine salt as described in Examples 1 and 2, the acid form of the penicillin and the procaine base may be used. The biosynthetic penicillin in acid form is obtained by extraction of the acidified broth.

The procaine salt of n-butylmercaptomethyl penicillin represented by the following formula in the form of its sulfate salt dissolves in the aqueous phase. The amyl acetate layer is separated from the aqueous layer and the n-butylmercaptomethyl penicillin is recovered in purified form from the amyl acetate by extraction of the amyl acetate with cold dilute aqueous alkali.

By proceeding through the insoluble procaine 35 penicillin salt, substantial purification of the n-butylmercaptomethyl penicillin is effected, the degree of purification amounting to 25 percent or more. If a more greatly purified n-butylmercaptomethyl penicillin is desired, the procaine salt of the penicillin is recrystallized from alcohol or other suitable solvent prior to the recovery of the biosynthetic penicillin therefrom. Recovery of the n-butylmercaptomethyl penicillin from the purified procaine salt yields the biosynthetic penicillin in substantially pure form.

Example4 The procaine salt of ethylmercaptomethyl may be prepared as follows: n-butylmeroaptomethyl penicillin is obtained by growing a penipenicillin which may be represented by the following formula cillin-producing mold in a culture medium containing about 0.02 percent of N-(Z-hydroxyethyl)-n-butylmercaptoacetamide, and extracting the acidified culture medium or broth with amyl acetate. The amyl acetate is clarified with about 0.5 percent of decolorizing carbon or fullers earth and is concentrated by evaporation in vacuo. To about 4 liters of this amyl acetate solution containing about 3 g. of n-butylmeris obtained as follows:

A penicillin-producing mold is grown in a culture medium containing about 0.02 percent of the sodium salt of N-ethylmercaptoacetylvaline,

70 and the ethylmercaptomethyl-penicillin produced in the broth is isolated as its potassium salt.

To about one part of the potassium salt of the ethylmercaptomethyl penicillin dissolved in about 6 parts of Water is added a solution of about captomethyl penicillin in acidic form are added 7 one part of procaine hydrochloride in 3 parts of 5 6 Water. The crystalline precipitate of the. prohicles. Suitable vehicles forthe, provision of C e Sal f ethylmercaptomethyl penicillin injectable suspensions include aqueous and Which Separates is removed y filtration, Washed oleaginous vehicles, for example, water, and with a small amount of cold water and dried in vegetable oils such as cottonseed oil, sesame oil,

Vacuoand the like. As will be readily understood, the

Example 5 particle size of the salt in suspension should be The procaine salt of isoamylmercaptomethyl sufiiciently small to permit the particles to pass penicillin represented by the following formula easily through the lumen of a hypodermic needle OOH may be prepared from the sodium salt of isowithout packing within and blocking the needle. amylmercaptomethyl penicillin and procaine hy- Illustratively, a particle size which avoids blockdrochloride according to the procedure described ing of a -gauge needle is that which will pass in Example 4. through a ZOO-mesh screen.

The isoamylmercaptomethyl penicillin used in By way of illustration, an aqueous medicinal the preparation is obtained by growing a pen- 20 composition which upon intramuscular injection icillin-producing mold in the presence of about is capable of maintaining a therapeutically efp nt of 2- yd y t yD'- s y1m rfective biosynthetic penicillin blood ,level for Captoacetamidea period of about 24 hours comprises a suspension containing about 300 mg. of finely divided The procaine salt of cyclopentylmercapto- 25 procaine t of y pto y p methyl penicillin represented by I the following 1111 p 1111- Of Waterformula Since, as is known, penicillins are relatively un- Example 6 is prepared from the sodium salt of cyclopentylstable in the presence of appreciable amounts of mercaptomethyl penicillin and procaine hydromoisture, aqueous compositions containing the chloride in water solution substantially according novel procaine salts of this invention should be to the procedure described in Example 1. used within a comparatively short time after The sodium salt of the cyclopentylmercaptotheir preparation. For this reason it is often methyl penicillin used may be obtained by growdesirable to provide the procaine salts in oleing a penicillin-producing mold in the presence aginous vehicles. A suitable oleaginous composiof a small amount of a water-soluble salt of tion which will retain therapeutic potency over a cyclopentylmercaptoacetic acid. long period of time is prepared by suspending in Emmple 7 about 5 ml. of sesame oil 2 g. of the procaine salt of n-butylmercaptomethyl penicillin, ground to The procaine salt of n-hexylmercaptomethyl a suificiently small particle size so that all of penicillin represented by the following formula the material will pass througha ZOO-mesh screen.

COOH

may be pr par d fr m th potassium salt f n- Intramuscular injection of 1 ml. of this suspension hezylmercaptomethyl penicillin and procaine sulwill maintain a therapeutically effective blood fate in water solution substantiallyaccording to concentration of n-butylmercaptomethyl penithe procedure described in Example 1. cillin for at least 24 hours. 7

The potassium salt of the n-hexylmercapto- It is to be understood that the above-menmethyl penicillin used may be obtained by growtioned therapeutic compositions are given by ing a penicillin-producing mold in a culture way of illustration only and it will be apparent medium containing about 0.02 percent of N-(2- to those skilled in the art that numerous modihydroxyethyl)-n-hexylmercaptoacetamide, and fications and variations of the above medicinal isolating the penicillin as the potassium salt. compositions may be made.

For therapeutic purposes, the procaine salts of 5 I claim as my invention: the biosynthetic penicillins of this invention pref- 1. The procaine salt of a biosynthetic penierably are administered intramuscularly as finecillin represented by the formula OOH 1y divided suspensions of the salts in liquid vein which R represents a member of the group r 7 8 consisting of aliphatic hydrocarbon radicals 2. The procaine salt of n-butylmercaptohaving from 2 to 5 carbon atoms, saturated carmethyl penicillin represented by the formula OOH bocyclic hydrocarbon radicals having from 5 to 3. The procaine salt of allylmercaptomethyl 6 carbon atoms in the ring and a total of from penicillin represented by the formula CODE 5 to 7 carbon atoms, and the monohalogen sub- 4. The procaine salt of cyclopentylmercaptostitution products of said radicals. methyl penicillin represented by the formula OOH HARLEY W. RHODEHAMEL, JR.

REFERENCES CITED The following references are of record in the file of this patent:

Drug and Cosmetic Industry, November 1947, page 595. 

1. THE PROCAINE SALT OF A BIOSYNTHETIC PENICILLIN REPRESENTED BY THE FORMULA 